finch



UNITED sawrns QFFIOE.

LEON S. FINCH, OEDOVER, NEW JERSEY, ASSIGNOR TO HERCULES BOWDER COMPANY, OF-WILMINGTO1\T, DELAWARE, A CORPORATION OF DELAWARE.

PROCESS OF MAKII N'G- CYANOGEN COMPOUNDS.

No Drawing.

citizen of the United States, residing at- Dover, countyof Morris, and State of New Jersey, have invented a new and useful Improvement in Processes of Making Cyanogen'CoInpounds, of which'the following is a full, clear, and exact description.

The manufacture of cyanogen compounds nitrogen to react with carbon and an al ali metal or alkaline earth compound, with or Without the use of iron as a catalytic material, has long been known and has even been practised on a commercial scale in Europe, but the economical execution .of the process, on, a commercial scale,

has vbeen hindered-by the relatively small, irregular and uncertain yields of the cyanogen compound, by losses in distillation of encountered in economically utilizing the the alkali metal salts, and by the difliculties cyanogen compound produced. The production of ammonia by adding water to the 'cyanid and distilling is quite obvious, but

Where the alkali cyanid is more or lcss impure, as is inevitable when it is produced by the foregoing process, none of the known distillation processes is effective. While a practicable process for'the hydrolysis of ammonia from alkali metal cyanid and ferrocyanid are set forth in applications Serial No.'246,279, filed July 23, 1918, by Carl F.

. 'Bierbauer and Leon S. Finch, and Serial No. 246,360, filed July 23, 1918, by Leon S. Finch; other important factors essential to the successful commercial execution of the nitrogen-fixing or cyanid-forming process, which have not been, until recently, worked out, are the details of construction of the apparatus and the selection of the proper form of carbon and its combination with a proper proportionof iron. The present 1nvention relates to this latter aspect of the,

problem and has for its object to utilize carbon in such form, and iron in such proportion, as will produce relatively large actual and theoretical percentages of alkali metal cyanid and of efficiency of fixation, and at the same time avoid the necessity for an excessively high temperature.

A reveiW of the patents and other literature on this subject discloses the fact that while all necessarily specify the use of ca bon and a few the advisability of usin it in a porous form, and while a great variety of forms of carbon has been suggested, there Specification of Letters Patent.

is apparently no appreciation of the fact that there is a vast, difi'erence in the efficiency of the different forms of carbon. Again, while the importance of using iron as a catalyzer has been recognized by some patentees, most of them have either failed to specify any particular proportion of iron relative to the carbon-alkali metal compound mixture, or if they have undertaken to fix the proportion, have recommended, with one or two exceptions, too large a proportion. The present invention is founded primarily on the discover that with active forms of carbon, having t e property of absorbing and condensing gases within their pores, the contact is so intimate that the reaction takes place as though the materials sodium (for example), nitrogen, iron and carbon-were present in their nascent state; thereby preventing the distillation of sodium salts at a temperature at which charges made of less active carbon give a considerable loss of sodium by distillation. It is usually impracticable to use a charge composed exclusively of carbon in its most active form, and my invention is founded on the further discovery that a small amount of active carbon will activate a large amount of inactive carbon. Hence the preferred embodiment of my invention involves the use of a mixture of relatively active carbon and normally relatively inactive carbon.

While, with the use of carbon in the form specified, a fair yield of' cyanid may be obtained by using an excessive proportion of iron as a catalyzer, higher and purer yields are obtainable if the proportion of iron is reduced to a relatively small percentage. My invention, therefore, in its more specific embodiment, contemplates the .use of carbon in the form explained in connection with the employment of iron, the proportion of which must not exceed a specified maximum. With the foregoing explanation, the in A current of pure nitrogen (which may be obtained by passlng atmospheric air over copper) is caused to pass over the above Patented Aug. 12, 1919. V Application filed October 7, 1918. Serial No. 257,287.

charge for about three hours. At the end of that period the amount of sodium cyanid actually produced will be a very large percentage of the theoretical.

In the mixture, the molasses is carbonized in the reaction chamber and serves to acti' vate the soft coal, which alone is much less active. Cheap and efiective substitutes for molasses are molasses Waste and Stei'lins waste. Other forms of active carbon may be used to advantage, as, for example, cocoanut shell flour. Other forms of relatively inactive carbon may be used, as, for exam ple, charcoal or lignite.

The use of an active vegetable carbon. must not be confused with the use of an indifferent form of carbon in a more or less highly. porous condition, which has heretofore been recommended. Thus, charges of coke can be made mechanically so that they are extremely porous, but coke is one o1 the least efiicient of all forms of carbon, and its use in a highly porous state, While increasing its low efiiciency, does not render it actually efficient. The most porous coke does not approach in ethciency theiorm of carbon used in my process. In fact, porosity, in the common acceptance of the term, promotes, rather than restrains, the distillation of sodium salts.

The proportion of sodium carbonate (or other alkali metal or alkaline earth compound) may vary from twenty-five to forty per cent. The proportion may go outside this range, but the use of a smaller proportion of sodium carbonate of course reduces the absolute yield of cyanid, While the use of a larger proportion of sodium. carbonate reduces the percentage of the actual yield to the theoretical yield. The preferred percentage is about thirty per cent.

The percentage of carbon niav vary from forty-five to sevent per cent, the preferred percentage being a out sixty.

The preferred relative percentages of materials in the mixture depends somewhat upon the source of the carbon that is utilized and such percentages may be stated more accurately by reference to the carbon content in the completely cyanized material. For example, it part of the carbonaceous material is liquid or of cellulose origin, it will carbonize in the furnace and the Weight of the carbon Which is formed will be much less than the Weight of the original material. Hence, a better explanation of the percentages is that the proportions of the mixture should be so adjusted rial is completely cyanized the carbon content will vary from 4:0 to 50 per cent.' the total alkali content, when figured to alkali metal cyanid, will vary from 4-5 to 55 per cent; While the iron content Will vary from 5 to 15 per cent.

Iron, preferably in the form. of iron scale,

that when the mateshould be used as sparingly as possible, so long as it is present in sufiicient quantity to promote the reaction to its maximum extent. About 10 per cent. is ample, but as above stated, it may be from 5 to 15 per cent. It is desirable to reduce the percentage of iron not only because a smaller percentage ofiron down to about ten per cent. gives higher yield of cyanid, but also because the presence of iron in the cyanid mixture is undesirable because of the tendency to form ferro-cyanid, especially after the addition of Water prior to distilling to ammonia. The hydrolysis of ferro-cyanid to ammonia is much more diliicult than the hydrolysis of cyanid to ammonia, and henceit is desirable to minimize the production of ferro-cyanid. This, of course, can be done in another Way, namely, by the entire elimination of iron from the original charge. If, however, this be done, the temperature of conversion is considerably higher, making it ditlicult not only to practise the process economically, but to provide receptacles for the charge that will be resistant to the excessively high heat. In this connection, I have also dis covered that the beneficial eflect of iron in reducing the temperature of reaction is negligible if the proportion of iron be increased beyond about ten per cent.

Another advantage attending the use of active carbon which T have discovered is that it enables nitrogen to be fixed at a lower temperature than When more inactive carbon is used.

It will be understood, from the foregoing explanation, that the bases of my invention are the discovery of the relatively greater efficiency of active vegetable carbon, the dis covery of the capacity of such active carbon to activate normally relatively inactive carbon, the discovery that the use of active carbon enables nitrogen to be fixed at a lower temperature than When more inactive carbon is used, the discovery of the proportions oi the components of the mixture necessary to efiiciency, and the discovery that a mixture of relatively active and relatively inactive carbon with a relatively small percentage of iron constitute the most eiiective and economical agent, in connection withan alkali metal or alkaline earth compound, for the fixation of nitrogen and the manufacture of cyanogen compounds.

While iron forms the most efiicient catalyzer, l have found it practicable to use other metals, alone or combined with iron, as, for example, iron scale and cobalt oxid.

It is highly desirable to keep the sulfur content'of all mixtures as low as possible. The presence of a considerable amount of sulfur interferes with the catalysis of the reaction, and also, when filtering, causes the conversion of some sodium cyanid to sodium ferro-cyanid.

soluble alkali metal compound and carbon in the presence of a catalyzer, which comprises utilizing a mixture of relatively active carbon and carbon which alone is relatively inactive but which is activated by the relatively active carbon.

2. The process of forming a cyanogen compound by the reaction of mtrogen with a soluble alkali metal compound and carbon in the presence of a catalyzer, which comprises utilizing a mixture of a normally-relatively inactive carbon and a carbonaceous material which by the heat of the reaction chamber is reduced to a relatively active carbon and activates carbon.

3. The process of forming a cyanogen.

compound by causing nitrogen to react with a mixture of a soluble alkali metal compound, a relatively active carbon and a normally relatively inactive carbon which is activated by the relatively active carbon, in the presence of catalytic material comprising less than twenty per cent. of the charge.

4. The process of forming a cyanogen compound by causin nitrogen to react with a mixture of a solu le alkali metal compound, a relatively active carbon and a normally relatively inactive carbon which is activated by the relatively active carbon, in the presence of catalytic material comprising approximately ten per cent. of the charge.

5. The process of forming a cyanogen compound by causmgnitrogen to contact with a charge comprlsing from twenty-five to forty per cent. of an alkali metal comof carbon and less the relatively inactive V pound, from forty-five to seventy per cent. than twenty per cent. of catalytic material.

The process of forming a cyanogen compound by causing nitrogen to contact with a charge compr sing from twenty-five to forty per cent of an alkali metal compound, fr m forty-five to seventy er cent. of carbon part of which is normally relatively active and part of. which is normally relatively inactive, and less cent. of catalytic material.

7. The herein described process of formthan twenty per ing a cyanogen compound by causing nitro gen to contact with a charge comprismg an alkali metal compound, carbon and catalytic material, in WhlCh the proportions of the mixture are so adjusted that when the material is completely cyanized the carbon content will vary from thirty-five to fiftyfive per cent., the alkali metal content from forty to sixty per cent., and the iron less than twenty per cent.

8. The herein described process of forming a cyanogen compound by causing nitrogen to contact with a charge comprising an alkali metal compound, carbon and catalytic material, in whlch the proportions of the mixture are so adjusted that when the material is completely cyanized thecarbon con tent will vary from forty to fifty per cent., the iron from five to fifteen per centrand the alkali content from forty-five to fifty-five per cent.

9. The' process of forming a cyanogen compound by causing nitrogen to react with hand, at Kenvil, N. J., on 

